JPS5947270B2 - Light reflector detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light reflector detection device for detecting a light reflector such as a small piece of aluminum foil, and is a device that can be applied to, for example, a registered mail number slip detector for an automatic registered mail acceptance machine.

A conventional light reflector detection device will be explained.

FIG. 1 shows a schematic configuration diagram thereof, in which 1 is a photosensor block, Sl, S2 . Planar photosensors 2 made of Sn, such as solar cells with wide directivity and approximately equal sensitivity, are pasted on two planes.

On the other hand, light emitted from a filament lamp 3, which is a linear light source, is condensed by a lens 4 and becomes a thin streak-like light beam 6 on an object 5 to be detected.

Since the reflected light 7 goes in various directions depending on the inclination of the detected object 5, the photosensor block 1 has a large area, and the reflected light 7 is directed from the light reflector 8 on the detected object 5.
It is designed to always receive light.

When the light beam hits the aluminum foil of the light reflector 8, it reflects well, so one of the sensors 2 of the photosensor block 1 receives a considerably stronger light than the light reflected from other parts of the object to be detected. is correct.

Fig. 2 is a circuit diagram of a conventional detection device, in which sl, s2, and sn of the photosensor 2 are diodes DA1 and DA2.
. . . The photosensor 2 connected to the maximum value selection circuit 9 composed of DAn and receiving the strongest light among the reflected light T from the object to be detected 5 will output the highest output voltage. .

The output voltage A is input to an amplifier 10 and amplified, and the output B, which has passed through a differentiator circuit composed of a capacitor 11 and a resistor 12, is compared with a comparison voltage E□ by a comparator 13.

FIG. 3 shows the relationship between the outputs A and B and the output C of the comparator 13 when the detected object 5 is moved in the direction of the arrow X in FIG. 1.

The output A of the maximum value selection circuit 9 when the light from the filament lamp 3 hits the surface of the object to be detected 5 is el, and the light reflector 8
If e2 is the time when light hits the surface of
A pulse-like voltage is obtained.

el<El<e2-el...Song (1) By the way, such a conventional detection device has the following problem.

If the detected object 5 is a white envelope or the like with a large thickness and a lot of reflected light, the distances between the filament lamp 3 and the detected object 5 and between the detected object 5 and the photosensor block 1 will decrease, so that the distance from the detected object 5 will be reduced. The amount of reflected light 7 increases.

Therefore, there is a case where e1>El, and a miss pulse Ep appears at the output C of the comparator 13 as shown in FIG.

Furthermore, if cellophane tape is attached to the object to be detected 5, light may be reflected on the surface and an output A similar to that obtained when a predetermined light reflector 8 is detected may occur, resulting in a detection error.

Furthermore, in order to detect the reflected light even when the aluminum foil is facing in various directions, a fairly large photo sensor block 1 is required, which requires a large number of sensors.
The cost will be high.

The present invention proposes a light reflector detection device that can solve these detection errors and reduce the number of sensors, and a practical example thereof will be described below.

In Figures 5a, b, and c, 14 is the object to be detected;
15 is an aluminum foil as a light reflector provided on the object to be detected 14, and 16 is a sensor unit.

The sensor unit 16 is installed facing the belt conveyor 17 for moving the detected object 14, and on the substrate 18 of the sensor unit 16, highly directional photosensors 19 equipped with lenses etc. are arranged at equal intervals to move the detected object 140. Arranged in one column across the width,
On both sides, there are 20 filament lamps and 2 frosted glasses.
A surface light source unit 23 composed of a cover 22 whose inner side is painted white is disposed.

For example, standard size mail is 14 to 23.5 crrls in length and 9 in width.
~12 Crrl x thickness 1 crn or less, and when the detected object 14 is moved in the length direction (direction of arrow Y in FIGS. 6 and 10) by the belt conveyor 17 and detected by the sensor unit 16, The detection range of sensor unit 16 is limited to 12 crn within kites 24 and 25.

Each of the photosensors 19 81 to S21 arranged in one row has a directivity of about 9 degrees, and the detected object 14 directly below it has a directivity of about 9 degrees.
For example, when the distance between the sensor unit 16 and the detected object 14 is 30 mm in FIG.
It senses only inside the circle.

The mounting pitch p of the photosensor 19 is 6tnx, and the size of the aluminum foil 15 is 12mm x 12mm, so
As shown in Figure 5a, place an aluminum foil 1 directly under the photosensor S5.
5, the adjacent photosensors S4 and S6 slightly detect the aluminum foil, but the photosensors 83 and S7 do not.

Also, if the aluminum foil is placed exactly between photosensors S5 and 86, the same intensity of reflected light will enter both photosensors S5 and 86, but the photosensors S4*S7 on both sides will receive reflected light. Not detected.

As shown in Fig. 6, when the aluminum foil 15 is tilted, each photosensor has directivity only within the shaded range, but since light is emitted downward from the surface light source unit 23 in various directions, reflected light and Can receive light.

As mentioned above, the width of a regular mail piece is limited to 12 cm, so in this case, there will be a total of 21 photosensors S□ to S2□.

FIG. 7 is a block diagram of the detection circuit, and the detection principle will be explained according to the diagram.

The light sources L□ to L4 in the surface light source unit 23 emit light from the power source E3.

Photosensors 81 to S2□ are divided into four blocks every third, and each block has diodes DD, to DD6. D
E1-I) E5. DFl-DF5. It is connected to maximum value selection circuits 26 to 29 of sensors configured by DG□ to DG5.

If there is an aluminum foil 15 directly below the photosensor S5 as shown in Fig. 5a of Kintetsu 5, and there is no other light reflector on the object 14 to be detected, the outputs D-G of the four maximum value selection circuits 26 to 29 teeth,
The output value is the output value of the photosensor S5 that has detected the aluminum foil 15, and the output E is smaller than the output value since the characters and patterns on the detected object 15 have been detected.

Output FK is the output of S6, and output G is S6.
4 is the output, but since these are detecting a part of the aluminum foil and the letters and patterns on the mail, the output value is larger than the output E, but it is smaller than the output E, and is about the same size. .

30 to 33 are differential amplifiers whose output is zero when the input difference is zero.

The output E is input to the differential amplifier 30.31 as shown in the figure, and the outputs F and G are input to the differential amplifier 32.33 as shown in the figure, so the output of the differential amplifier 30 is positive. Maximum, differential amplifier 31 is negative maximum, differential amplifier 32 and 3
The output of 3 is almost zero.

Then, the output of the differential amplifier 30 is selected as the output H of the maximum value detection circuit 34 composed of diodes DH1 to DH4.

When the value of the output H is larger than the comparison voltage E2, the output J of the comparator 35 appears.

Therefore, when the aluminum foil 15 passes directly under the photosensor S5 as shown in FIG. 5a, the timing chart of each output DJ is as shown in FIG. 8.

Next, a case where the aluminum foil 15 passes between the photosensors S5 and 86 will be described.

In this case, the photosensors S5 and 86 sense the reflected light, and outputs appear at the outputs F and F, but as described above, the photosensors S4 and 87 do not sense the reflected light.

Therefore, the outputs of the differential amplifiers 30 and 32 reach a maximum value at approximately the same value when passing through the aluminum foil, and an output H appears.

Then, the output H and the comparison voltage E2 are compared, and the detection output J
appears.

A timing chart at that time is shown in FIG.

As can be seen by comparing the output H in FIG. 8 with the output B in FIG. 3, in this embodiment, there is no miss pulse at the beginning of the passage of the object 14 to be detected.

Furthermore, when light is reflected to the sensor unit 16 by the cellophane tape 36 on the detected object 14 or the cellophane 37 in the transparent window of a window-perforated envelope as shown in FIG. Greater than the photo sensor spacing.

Therefore, since the difference in the amount of light received by adjacent photosensors 19 is compared, the difference becomes zero, and error output pulses are unlikely to appear even in such a case.As a result, for example, when processing envelopes, etc. Errors in detecting number tags on envelopes without number tags have almost disappeared.

Note that since the difference in photosensor output is detected, the distance between the photosensor 19 and the detected object 14 is approximately 20 to 30 m.
Therefore, even if the aluminum foil 15 is tilted as shown in FIG.
The number can be reduced to one, and even if the surface light source unit 23 is included, the cost can be reduced.

The circuit diagram of an embodiment in which 21 photosensors are divided into four blocks is shown above, but the same principle can be applied even if every two photosensors are divided into three blocks as in the embodiment shown in Fig. 11. The aluminum foil 15 can be detected.

That is, as shown in FIG. 11, the photosensor is connected to diodes DK□ to DK7. DLIDL7゜ is connected to the sensor maximum value selection circuits 38 to 40 composed of DM1 to DM7, and their outputs are connected to differential amplifiers 41 to 46 for L and M, respectively.
Connect to.

Now, when the aluminum foil 15 passes directly under the photosensor S5 as shown in FIG. 5a, the output becomes the output value of the photosensor S5 as shown in FIG. 12, which is the output K.

In the photo sensor S4.M, the photo sensor S4 detects a part of the edge of the aluminum foil 15. The output value of S6 is
The value is smaller than the output, and they are almost equal.

Therefore, the outputs of the differential amplifiers 42 and 45 are almost equally maximum, and this value becomes the output N of the maximum value selection circuit 47.

The output N is compared with the comparison voltage E4 and the output p of the comparator appears.

FIG. 13 shows a timing chart when the aluminum foil 15 passes between the photosensors S5 and 86.

It will be clear that detection is possible in this case as well in the same manner as in the above embodiment.

The above is an example in which the photosensor is divided into three or four blocks, but by increasing the number of differential amplifiers,
Aluminum foil can be detected using the same principle even if divided into five or more blocks.

Furthermore, in the explanation so far, we have limited to the detection of a small piece of aluminum foil with a square size of 121 rLm, but its shape may be round or triangular, and its size is not limited to 12 mrn. Detection can be easily performed by changing the pitch of the photosensor arrangement and the distance between the detection target and the photosensor.

Further, although the case where the sensor unit 16 is fixed and the detected object 14 is moved has been described, the detection can be performed in the same way even if the detected object 14 is fixed and the sensor unit 16 is moved.

The light source may be a surface light source such as an EL cell.

As described above, according to the present invention, the sensor unit may have a relatively simple configuration, and the arrangement pitch of the photosensors can be made to correspond to the size of the light reflector. If it is reflected, it will be canceled and there will be no false detection, and there will be no false detection at the beginning of the object to be detected, making it possible to perform accurate detection operations and at the same time, the sensor unit itself can be made as inexpensive as possible. Therefore, it is possible to provide an industrially excellent light reflector detection device.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the main part configuration of a conventional light reflector detection device, FIG. 2 is a circuit configuration diagram of the conventional example, FIGS. 3 and 4 are timing charts thereof, and FIG. 5a. b and c show an embodiment of the present invention; FIG. 6 shows a cross-sectional view showing the arrangement of the sensor unit and the object to be detected; a bottom view of the sensor unit; and a side view of the sensor unit; FIG. 6 shows a case where the light reflector is tilted; 7 is a circuit configuration diagram of this embodiment, FIGS. 8 and 9 are timing charts thereof, FIG. 10 is a plan view showing the arrangement of the sensor unit and the object to be detected, and FIG. The figure is a circuit configuration diagram of another embodiment of the present invention, and FIGS. 12 and 13 are timing charts thereof. 14...Detected object, 15...Aluminum foil (light reflector), 16...Sensor unit, 18
...Mounting base L 19. s1~S21...
... Photo sensor, 23 ... Surface light source unit, 26-29 ... Maximum value selection circuit, 30-33
... Differential amplifier, 34 ... Maximum value detection circuit, 35 ... Comparison circuit, 38 to 40 ...
...Maximum value selection circuit, 41-46...Differential amplifier, 47...Maximum value detection circuit, 48...
・Comparison circuit.

Claims (1)

[Claims] 1 A device for detecting the presence or absence of a light reflector having a specific shape, which includes a surface light source for irradiating light onto the light reflector to be detected, and receiving light reflected from the surface light source of the light reflector. a substrate for arranging and fixing the photosensors in a straight line, and selecting the photosensors every integer of two or more to form a sensor block, and forming a sensor block for each sensor block. a first maximum value selection circuit that selects the output of the photosensor that has received the strongest reflected light; a differential circuit that detects a difference in output voltage between the first maximum value selection circuit; It has a second maximum value selection circuit that detects the maximum voltage among the outputs of the circuit, and a settling circuit that sets the output of the second maximum value selection circuit and a preset voltage value, and The sensor installation interval and the distance between the reflective surface of the light reflector and the photosensor are set so that the number of photosensors that receive reflected light from the entire area of the light reflector is 3 or less at most. Reflector detection device.